PATIKIL 8" (200mm) to 4" (110mm) Duct Reducer Connector, Heating Cooling Ventilation Tube Fire-Resistant Increaser Adapter Pipe Fitting for Vent System

Excellent and as advertised done the job I wanted it for.

Did exactly what I needed it to do

It's well made and a perfect fit. bought a different types and i had to modify and cut to make fit. love it

As stated in previous reviews this products outside diameter is too large to connect to HVAC ducting properly.

I don't think the size measurement is accurate, particularly the 8", It seems like it's a quarter of an inch short making it almost impossible to perfectly fit into an 8". The 4" fits great, the 8" is the issue. Also, the inside of the plastic is way too polished and slippery making it difficult for the duct to stay in place, no matter how tight I fasten it, it just slides right out. Sorry, mate, have to return this item.UPDATE on my previous review: I used a duck tap to secure it. Seems to work perfectly thus far.

This duct reducer is not the standard 4” or 8” size. Also received a returned unit based on the return sticker still on it. I would avoid this product if you’re using a standard 8” or 4” ducting